Train control system for transit vehicles

ABSTRACT

A plurality of biased, direct curent control relays, each requiring a predetermined high or low level of operating energy, are coupled across a two conductor signaling channel extending along the nonconducting right-of-way. A first conductor is divided into insulated sections of preselected lengths corresponding to right-of-way speed requirements. The midpoint of a direct current wayside signal energy source is connected to a common bus lead to which the second channel conductor is also connected. Either the positive and negative end terminal of the source is selectively connected to each first conductor section through a preselected resistance to fix the high or low voltage level and the polarity of the applied control signal. The train relays selectively respond to the polarity and voltage level of the received signals in accordance with each relay&#39;&#39;s characteristics, and accordingly control various train operating functions such as speed and door opening. In one alternate form, only train speed is controlled by the biased relays while the doors are controlled by a reed relay influenced by a magnet mounted at the train stopping point on each station platform. The train relays in multiple, also serve as a shunting circuit for releasing a wayside train detector relay, connected between each first conductor section and the common bus, to register train occupancy. These detector relays enforce station-to-station train separation but train speed is otherwise selected only in accordance with the physical character of the right-of-way.

Linderman [4 1 May 20, 1975 1 TRAIN CONTROL SYSTEM FOR TRANSIT VEHICLES [75] Inventor: WilliamgLLinderman, Murrysville,

Assignee: Westinghouse Air Brake Company,

Swissvale, Pa.

Filed: Oct. 9, 1973 Appl. No.: 404,766

[56] References Cited UNITED STATES PATENTS 1/1956 Stafford 246/182 R 12/1959 Hughson 246/63 C 6/1962 Pascoe..... l/1966 Allison 2,731,550 2,915,623 3,041,448 3,229,086 3,387,880 6/1968 3,710,100 l/l973 Perry 246/28 R FOREIGN PATENTS OR APPLICATIONS 492,833 4/1919 France 104/153 Primary Examiner-Lloyd L. King Assistant Examiner-Rcinhard J. Eisenzopf Attorney, Agent, or Firm-A. G. Williamson, Jr.; R. W. Mclntire, Jr.

[57] ABSTRACT A plurality of biased, direct curent control relays, each requiring a predetermined high or low level of operating energy, are coupled across a two conductor signaling channel extending along the nonconducting right-of-way. A first conductor is divided into insulated sections of preselected lengths corresponding to right-of-way speed requirements. The midpoint of a direct current wayside signal energy source is connected to a common bus lead to which the second channel conductor is also connected. Either the positive and negative end terminal of the source is selectively connected to each first conductor section through a preselected resistance to fix the high or low voltage level and the polarity of the applied control signal. The train relays selectively respond to the polarity and voltage level of the received signals in accordance with each relays characteristics, and accordingly control various train operating functions such as speed and door opening. In one alternate form, only train speed is controlled by the biased relays while the doors are controlled by a reed relay influenced by a magnet mounted at the train stopping point on each station platform. The train relays in multiple, also serve as a shunting circuit for releasing a wayside train detector relay, connected between each first conductor section and the common bus, to register train occupancy. These detector relays enforce station-to-station train separation but train speed is otherwise selected only in accordance with the physical character of the right-of-way.

10 Claims, 2 Drawing Figures I r PROPLLSION RETURN RAIL\ ON PL TFORM I AT\ [J BT\ J I T1 rJ $T\ (J 2AT\ .BRB SIGNAL RAIL 2AR3 ATR BTR BRZ 2ATR c c c l 1 F 1 TB 1 T 1 $00 one CLDQDSOERD weh lillfiN 1B1|||ll||||l1- N gggs mgg TN IS IN EFFECT FROM STAT B WAYSID C TRNN CARRIED Do OD; I Y .1 B 1s DETECTED c l Ls DOOR COMMAND SIGNAL Ea LSP oooas OPEN CONTROL Ms 5% N OVM 1 {EL MSP N B B l1 SPEED COMMAND SIGNAL TRAIN CONTROL SYSTEM FOR TRANSIT VEHICLES BACKGROUND OF THE INVENTION My invention pertains to a train control system for transit vehicles. More particularly this invention pertains to train control system for personal rapid transit type vehicles or trains moving along a concrete rightof-way.

Personal rapid transit systems (PRT) are becoming more common and are being used to provide small group transportation in relatively restricted areas, normally at low speed around a closed loop right-of-way. By way of example, they may be used in such places as airports between main and auxiliary terminals or gate areas, in large shopping complexes, and on large and spread out university campuses. They may also be used in central business districts to provide transportation between terminal stations of more conventional commuter or rapid transit systems. These PRT systems are relatively low speed, small vehicle operations which allow simple train detection and/or separation and speed controls. However, such train detection and speed control arrangements are complicated by the normal use of concrete right-of-way or guideways on which move rubber tire vehicles. Thus prior detection and control arrangements which are dependent upon wheelaxle shunts across conductive rails supporting the vehicle wheels cannot be used. Nevertheless, automatic failsafe detection and train control operation is not only desirable but necessary in such PRT installations from an economic standpoint. Therefore an efficient and economic arrangement for speed control including train detection or separation is required for PRT systems where conventional prior art control methods are not practicable or even possible.

Other objects, features, and advantages of my invention will become apparent from the following specification when taken in connection with the accompanying drawings and appended claims.

SUMMARY OF THE INVENTION In practicing my invention, each separate vehicle or the lead vehicle of a train in the transit system is provided with controlapparatus which comprises a plurality of relays, each relay having distinctive operating characteristics. As specifically shown and described, these characteristics consist of the voltage level and polarity of the direct current signal at which the relay is properly energized to operate. Each such relay controls a particular and different function of the train operation, such as various speed levels and door control. The circuit network controlled by the train carried relays is designed to check to assure that only one function is selected for control at any one time. The signals for operating the relays are received from wayside apparatus which also serves to detect the location of the trains on the right-of-way and thus determines the advance traffic conditions for each specific train. The wayside origi- Still another object of the invention is a control system for regulating speed and station stop of transit vehicles moving on a concrete right-ofway.

It is also an object of my invention to provide a speed and station stopping control system for PRT trains comprising rubber tire vehicles which move on concrete or other insulated right-of-way.

A still further object of the invention is a movement control system for PRT trains using a sectionalized sig nal rail and one propulsion rail as a channel for transmitting command signals from wayside to the train and for detecting the train positions.

A still further object of the invention is apparatus for controlling the speed, station stopping, and door open ing of PRT trains utilizing a sectionalized signal connated signals have predetermined characteristics in accordance with the physical condition of the right-ofway and thus represent an allowed speed at which the train may move. In addition, the transmitted wayside signals may also include control requirements for station stops, door control operation, and other similar functions. Normally, the speed allowed in each section is preset in accord with the physical character of the right-of-way, e.g., tangent or curve, station approach or departure, etc. However, the wayside apparatus, which determines the advance traffic conditions through various train occupancy checks, normally establishes station-to-station blocking with a go or no-go decision to determine when the signal is supplied to a particular train to depart from a station platform.

Because the disclosed system is arranged for controlling rubber tire vehicles moving along the concrete guideway, in other words, vehicles which are insulated from the right-of-way, the wayside signals are transmitted to a train over a channel comprising a special signal conductor or rail and the return propulsion conductor also utilized in the alternating current propulsion system for the train. The train-carried apparatus is thus coupled across this two rail channel. The signal rail is divided into sections of predetermined lengths so that speed selection may be transmitted by selecting the signal characteristics for eachv station. As specifically shown, the applied direct current signal voltage has preselected voltage level and polarity characteristics which determine the speed control exercised or other function to be actuated. The train detection arrangement uses the same transmitted direct current signals but includes detector or track relays which are normaly energized over the signal rail section only with a return path for the energy through a system common bus connection to the signal source. The train apparatus shunts the section detector relay by a lower resistance path through the relays on the train and the return propulsion rail to the same common bus connection to the signal source. Each normally energized detector relay threrefore releases to detect the presence of the vehicle or train within its corresponding right-of-way section.

claims, I shall describe more specific arrangements embodying my invention in detail with reference from time to time to the accompanying drawings in which:

FIG. 1 is a diagrammatic circuit illustration of a traincarried apparatus and associated wayside control circuits embodying one form of the train control system of my invention.

FIG. 2 is another diagrammatic illustration of a traincarried apparatus embodying a second form of the invention. v

In each of the drawing figures, similar reference characters designate the same or at least similar parts of the apparatus. In each of the embodiments, the traincarried apparatus includes a local source of direct current energy for operating relays and such other apparatus as necessary. Since the use of such direct current operating energy sources on trains is conventional and any one of several types may be used, no specific source is shown. However, connections to the positive and negative terminals of these train-carried energy sources are designated by the reference characters B and N, respectively.

DETAILED DESCRIPTION OF THE APPARATUS Referring to FIG. 1, across the top, forming the signaling channel, are two parallel lines designating the two conductors or rails which extend along and parallel with the right-of-way or guideway of the PRT system, which is assumed to be a concerte structure on which run the rubber tire vehicles. The upper of the two conductors is the propulsion return rail for the alternating current propulsion energy which drives the vehicles. The second propulsion rail is not shown since it is not involved in the invention system. The lower of the two conductors shown is the signal rail which is divided into insulated sections at the point J, which may be actual insulation or air gaps in the rail structure. The vehicle or train-carried apparatus which is directly coupled to the rails is shown below the dot, dash line across the center of the drawing and comprises three speed control registry relays, HS, MS, and LS and a door open command relay DO. The speed control relays register, respectively, the high, medium, and low speed commands for the train. Each of these relays is a biased type and will operate, that is, pick up, only when the current flowing in the winding is in the direction shown by the arrow within the winding symbol. These relays also require different voltage levels for proper operation, as designated by the symbols HV and LV also shown within the winding. In other words, the HV relay HS is fully or sufficiently energized to operate only when the voltage applied thereto is at a relatively high level as compared with the voltage required for the operation of associated LV relay MS. The relays thus pick up only if the voltage level and polarity applied to the winding terminals is proper both as to level and direction. It will be obvious, however, that a low voltage relay will also pick up if the corresponding high voltage relay is sufficiently energized. The train-carried apparatus is coupled across the signal and propulsion return rails in section AT by pick up brushes which are illustrated by the arrow symbols terminating on the conductor or rail lines. These signal pick up brushes are similar or at least equivalent to the current or power pick shoes used on the third rail in conventional or rapid transit systems. It may also be noted that the windings of the four signal registry relays are connected in multiple across the two rails orconductors forming the signal transmission channel.

Other relays carried on the train include the medium and low speed repeater relays MSP and LSP, respectively. A circuit for energizing relay MSP extends from terminal B of the train-carried source over front contact a of relay MS, back contact a of relay DO, and the winding of relay MSP to terminal N of the source. Thus, provided the door open relay D0 is not picked up, relay MSP is energized and picks up each time that relay MS is similarly picked up. The winding of relay MSP is shunted by a capacitor to provide some slow release characteristics when the relay winding is deenergized. The energizing circuit for relay LSP includes front contact a of relay LS and the winding of relay LSP so that this relay basically is a direct front contact repeater of the low speed registry relay. However, the capacitor Cl is connected in multiple with the winding or relay LSP over back contact a of the relay itself. Thus capacitor C1 must be charged to a preselected voltage level before sufficient current will flow through the winding of relay LSP to energize this relay to pick up. This provides some pick up delay time to relay LSP after the initial closing of front contact a of relay LS. A zero velocity relay 0V is provided and energized by a simple circuit which includes a contact OD which closes when zero train velocity is detected by any one of several appropriate means which are conventional in the art. When relay 0V is energized and pick up, the closing of its front contact a energizes a zero velocity magnet OVM. This magnet is used to actuate a train presence detector contact along the wayside at each station location. Such a contact may be used for controlling the opening of the platform doors and for actuating the eventual departure operation of the train from the station. An arrangement such as this is shown in the copending application for Letters Patent of the United States Ser. No. 404,751, filed by Oct. 9, 1973 by H. L. Hathaway for a Train Detector and Control System, and having the same assignee as this present application.

The speed control circuits on the train are shown in a conventinal manner, only the specific circuit network including the contacts of the various speed relays involved in the invention being illustrated in detail. The conventional speed control apparatus of the train outputs a speed command signal, as indicated, over the upper line in the lower right. Over various circuit paths in the contact matrix of the speed relays and their repeaters, this signal is returned to a low, medium, or high speed signal control circuit which actuates the train apparatus to establish such a speed level for train movement. For example, when the relays are in the condition to which they are operated when the train is occupying section AT, as shown, a circuit path is complete from the speed command signal output over front contact a of relay MSP and front contact a of relay HS to the high speed control circuit. Similarly, when a me dium speed condition exists, front contact a of relay MSP remains closed but the circuit path extends over back contact a of relay HS to the medium speed control circuit. Under low speed conditions, the circuit path from the speed command signal output extends to the low speed control circuit over back contact a of relay MSP, front contact b of relay LSP, and back contact b of relay DO. This last contact is included to prevent the actuation of a low speed command when a door open condition exists since relay LS, having the same polarity characteristic as relay D0, will also be energized, as will be apparent later.

The brake control network is shown in a similar conventional manner. For purposes of this description, it is assumed that, when the brake command signal output is applied to the brake control circuit shown at the very bottom, the train brakes are held released. One circuit path for applying this signal extends over front contact b of relay MSP while a second path in multiple therewith includes front contact c of relay LSP. 1n the illustrated condition of the relays, since relay MS? is energized and its front contact b is closed, the brakes are held in their off condition. Relay MSP, of course, is energized for both the high and medium speed conditions and thus provides the brake release control under such speed conditions. Relay LSP then provides the brake release for a low speed condition. One other control circuit is provided on the train, that by which the door command signal is applied to the door open control circuit to actuate the opening of the doors of the train under a station stop condition. This circuit includes front contact b of relay 0V and front contact c of relay DO. Thus the door open command must have been received, on the train from the wayside signal channel and, at the same time, the zero velocity condition, that is, the completely halted condition of the train must have been detected.

1 shall now turn to the signal supply circuit shown above dot, dash line. A complete wayside arrangement for detection of the trains and the control of platform doors and other functions, as well as for applying the proper signals for transmission to the train apparatus, is shown in greater detail in the previously mentioned Hathaway copending application. Here sufficient detail is shown only for an understanding of the relationship and transmission of signals to the train. One train detector or track relay TR is associated with each section of the signal rail and is normally energized by circuit which includes that section of the rail and the signal battery. The signal battery shown to the upper left of the drawing is in the form of a split battery having a positive terminal TB, a negative terminal TN, and a center tap terminal C. This last terminal thus becomes negative with respect to terminal TB but positive with respect to terminal TN, in a well understood manner. It is noted that, in the extreme upper left, a connection from the propulsion return rail to terminal C of this battery is indicated. Although herein shown as a direct simple connection from rail to the battery, the copending application of Hathaway illustrates various fail-safe elements and specific connections which may be used in connection with the detection of trains but which need not be shown herein.

The train detection arrangement for signal rail section AT includes the train detector or track relay ATR which is normally energized by a circuit from terminal TB over front contact a of the advance section track relay BTR, a resistor ARI, rail section AT, resistor AR3, and the winding of relay ATR to terminal C. Under the train occupancy conditions specifically shown, the relay winding is actually shunted by the circuit from the pick up brush coupling to section AT through the windings of the train-carried relays in multiple and returning through the other brush coupler and thepropulsion return rail to terminal C of the battery. Thus the winding of relay ATR is shunted by a lower resistance circuit and the relay is released, as designated by the released condition illustrated for its contact a. This shunting is assured by preselectin g resistor AR3 connected in series with the relay winding, so that the path from the signal rail to terminal C through the resistor and relay winding has a much higher resistance than the corresponding multiple path through the windings of the train-carried relays. The detector track relay for each section of the right-of-way has a relatively similar normal energizing circuit including the corresponding section of the signal rail. It will be noted that each track relay between station areas or station platforms is energized over a contact of the track relay for the section in advance. The circuit for track relay STR associated with the station section ST includes front contact b of relay CTR, the track relay for the approach section. This arrangement of track circuit connections assures that, once released, no track relay can be energized until the train which caused its release has arrived and departed from the station platform at the exit end of the station block. It will also be noted that the signal applied to section CT is of a reverse polarity since terminal TN of the battery is connected through resistor CR2 to the rail and the polarity of the connections of the winding of relay CTR to terminal C through front contact a of relay STR are reversed.

The connections from terminals TB and TN to the various signal rail sections also provide signaling energy to the train-carried relays of any train occupying the corresponding section. The voltage level is determined by the series resistor in the connection from the signal battery terminal to the rail. These resistances increase by an order of magnitude as the suffix of the basic reference character R1, R2, and R3 increases in that order. Specifically, in one example, resistors of the R1 type are on the order of 60 to ohms, the R2 resistors are on the order of 500 to 700 ohms, whereas the R3 resistors are on the order of 4,000 ohms. In addition to the fact that the track relays to the rear of a train cannot pick up until the train has departed from the next station, it will be obvious that, prior to train arrival in section ST, the speed signal has been removed from this section of the signal rail by the opening of front contact b of relay CTR. Thus no speed signal is supplied to the train-carried apparatus when a particular train first enters this station platform section, which causes the train to brake to platform stop.

Two alternate circuit paths are provided for applying control signals to the rail of section St for further transmission to the train-carried apparatus. The first of these extends from terminal TN over a normally open contact ODC and through resistor SR1 to section ST of the rail. Contact ODC represents a relay contact which becomes closed while the platform doors are controlled to their open position, full details of which are shown in the copending Hathaway application. This contact opens when the open door command is removed after a predetermined period of time. Another alternate path for supplying energy to section ST extends from terminal TB over a normally open contact 800 and through resistor SR2 to the signal rail. Contact 560 represents a contact of a station gate open relay, which contact closes to authorize a train to depart from the station platform after all advance traffic conditions and local door positions are checked for safety. This contact closes and then reopens when the train initially occupics the first advance section such as section 2AT in the present illustration.

I shall now describe the operation of the apparatus shown in FIG. 1 as a train passes through the stretch of right-of-way shown. It is assumed that the train has occupied section AT, as shown by the brush symbols adjacent the two rails. The winding of relay ATR is thus shunted by the train-carried apparatus so that the relay is released, as illustrated by its contact a in its released or back position. Since this train is departing from a station assumed to the immediate left of the drawing figure, it is operating at the highest allowed speed in accordance with the signal picked up from the wayside. Since terminal TB is connected to signal rail section AT through an R1 type resistor, a positive polarity, high voltage signal is applied to the train-carried apparatus and relays HS and MS are thus properly energized to pick up. Relay MS closes its front contact a so that relays MSP is also energized and the circuit including front contact a of relay MSP and front contact a of relay HS is closed for selecting the high speed control. Further, the brake control circuit is complete, over front contact b of relay MSP, between the brake command signal output and the brake control terminal so that the train brakes are in their released condition. When this train enters section BT, relay BTR releases. Terminal TB is connected through an R2 type resistor to rail section BT so that the train now receives a positive polarity but low voltage level signal. Thus, on the train, relay HS releases, receiving insufficient energy to remain picked up. However, relay MS remains operated and its repeater relay remains picked up. Now the circuit over front contact a of relay MS? and back contact a of relay HS is completed so that the medium speed control circuit is selected. It may be noted in passing that front contact a of relay BTR interrupts the signal supply circuit for section AT which thus remains open until the train departs from the next station.

When this train enters section CT, relay CTR releases, since its winding is shunted from the signal source and, with the opening of its front contact b, release of track relay STR in the station platform section ST shortly follows. While in section CT, the train apparatus receives a low voltage but reverse polarity signal since terminal TN is connected through an R2 type resistor to the signal rail. Relay MS thus is reverse energized and releases, followed shortly by the release of relay MSP. Relay LS, however, is properly energized and picks up, closing its front contact a to energize the winding of relay LSP and capacitor C1 so that relay LSP shortly picks up. Relay DO remains released since insufficient energy is received, even though of the right polarity, to cause this relay to operate. Thus the low speed control circuit is selected over back contact a of relay MSP, front contact b of relay LSP, and back contact b of relay DO. This checks, of course, that a door open command has not been received and is not active so that is is safe for the train to continue to move. In the brake command control network, front contact of relay LSP replaces front contact b of relay MSP in holding the circuit network closed to continue the brakes in their released condition. Front contact 0 of relay LSP closes prior to the opening of the front contact b of relay MSP so that not even a brief brake application occurs.

When the train enters section ST, it receives no speed command since front contact b of relay CTR is already open. Relays LS and LSP release to open the low speed selection circuit. Since the opening of front contact c of relay LSP also interrupts the brake circuit network, brakes are applied and the train makes a normal station stop at the station platform. As soon as zero speed condition of the train is detected, contact OD closes to energize relay OV. Magnet OVM is now energized by the closing of front contact a of relay 0V to transmit a signal to the wayside apparatus which, as previously explained, actuates the opening of the platform doors. Thus, shortly after the train has stopped, contact ODC along the wayside closes since the door command has been received. The connection is now completed between terminal TN and rail section ST through resistor SR1. This causes a high voltage, reverse polarity signal to be transmitted which is received by the train-carried apparatus and properly energizes DO and LS which both pick up. Although relay LSP shortly receives sufficient energy to pick up, the open back contact b of relay DO interrupts the low speed selection circuit. However, the closing of front contact c of relay DO completes the circuit for actuating the opening of the doors on the train since front contact b of relay 0V is already closed. Thus the opening of the doors on the train matches the opening of the platform doors so that passengers may load and unload as they desire. Although the brake release network is completed by the reclosing of front contact 0 of relay LSP under these conditions, there is no corresponding speed command so that the train remains halted at the station platform. In addition, the open condition of the train doors may be used to assure that no movement of the trains occurs, e.g., by an alternate means or circuit for applying the brakes.

At the end of a predetermined timing period, contact ODC on the wayside opens and the high voltage, reverse polarity door command signal is removed from the rail. Relays DO and LS release, followed by the release of relay LSP. The low speed selection circuit is thus opened at front contact b of relay LSP and the brake circuit at front contact c of this relay. Very shortly, the proper advance traffic conditions having been detected, contact 560 on the wayside closes to initiate the train departure from the station. Terminal TB is now connected through resistor SR2 to rail section ST to apply a low voltage, positive polarity signal for transmission to the train-carried apparatus. Under these conditions, relay MS is properly energized and picks up, followed by the pick up of relay MSP since back contact a of relay D0 is now closed. The closing of front contact b of relay MSP completes the brake command circuit, the brakes are released, and the medium speed control circuit previously traced is again completed so that the train may move forward at this speed condition.

As the train departs from the station platform, it shortly occupies section 2AT and therein receivesa high voltage, positive polarity signal so that relays HS also picks up on board the train to select the high speed circuit for the train movement. When this train clears section ST, relay STR is energized, and picks up, by energy received from terminal TB over. contact 800. The closing of front contact a of relay STR completes the energizing circuit for relay CTR through rail section CT and this relay thus picks up. The closing of front ples of the train control system of my invention. In this contact b of relay CTR completes the normal energizing circuit for relay STR so that this track relay remains picked up. Contact 860 is held closed for a sufficient time for these actions to occur prior to its opening in response to the departure of the train. Further, the pick up of relay CTR closes its front contact a to apply sig nal voltage to rail section BT to thus energize relay BTR. This latter relay picks up, closing its front contact a to apply a similar signal to section AT which in turn energizes relay ATR. Thus the station-to-station block in approach to the station platform adjacent section ST, having been closed by the train, is now reset to its normal condition with all track relays energized. Under these conditions, a following train can now be authorized todepart from the preceding station to the left of the drawing and to proceed to the station section ST.

Referring now to FIG 2, I shall describe a second form of train-carried apparatus embodying the princispecific form, only-three of the train-carried relaysre: spond directly to thetrack voltage signals transmitted to the rails or conductorsfrorn the wayside. Across the .top of FIGQZ are again shown the signal and propulsion return rails which parallel the right-of-way for the vehicles. The propulsion return rail is againconnected to terminalC of the signal battery although the specific battery is not shown, it being equivalent or identical to rail connections are not shown since they have been previously fully described. With the battery connections shown, sections AT, BT, and 2AT are provided from the rails. Each of these relays requires a high level of voltage before it is sufficiently energized to operate, differing thus from the corresponding relays MS in the first form. The windings of relays HS and MS also provide the shunt connections across the signal and propulsion rails which cause the train detection relays to release upon train occupancy of the corresponding sec tion to detect the pressure of that train.

Relay LS is of the low voltage type and is connected to respond to a positive polarity signal only. The circuit for this relay across the brush contactors includes, in

series, back contacts a of relays HS and MS to inhibit the pick up of relay LS if either the. high or medium speed signal has been received. The circuit for relay LS also includes a time delay means or element designated by the conventional block LST. This time delay element is here used to delay the pick up of relay LS after energization of the winding, as is designated by the upward pointing arrows drawn through the movable portions of each contact of relay LS. The delay period is preset to include a desired period of door open time at the station platform plus a period of station stopping time from the medium speed level, as will become apparent shortly. For example, the door open time may be selected at 25 to 30 seconds plus a relatively equal stopping time so that up to a period of 60 seconds delay in the pick up of relay LS may be used. The time delay element LST may be any one several types known in the art which are usable here, including the use of an actual time element'relay in which the delay is incorporated within the relay winding itself. Other types inelude solid state devices, one shot multivibrators, resistor-capacitor networks, and similar arrangements.

i with high voltage signals, the first and the last being of positive polarity while section ET is provided with a reverse polarity signal. correspondingly, section ST opposite the station platform is provided with a low voltage, positive polarity signal. However, for section CT in approach to the stationplatform, the low voltage, re-

verse polarity signal is used only to provide a train oc- MS, and LS respond to the polarity andlevel of the voltage signal received from the signal rail but the door control relay D0 is controlled in another fashion which will be developed later. A safety feature is shown within the dash line block V which represents the train moving along the right-of-way. Two pick up contactors or brushes for the train-carried relays are connected or in Contact with each of the two rails. The'train-carried speed relays are then connected to the bus bar which joins the two brushes on each side in order to eliminate most if not all of the occurrences of lost contact or coupling between that particular rail and the rail pick up contactors. It will be seen that the windings of relays HS and MS are connected with opposite polarities across the rail contactor brushes so that they respond, respectively, to positive and reverse polarity signals The speed control network and apparatus is shown in a schematic fashion since various specific types of apparatus known in the prior art and of conventional nature may be used. The specific speed selection network consists in applying a desired signalfto the input of a comparator means which then functions to compare this desired speed with the actual vehicle speed signal received from an axle tachometer or other similar device. For example, if a high vehicle speed is selected,

a signal is applied from the corresponding high speed request input over front contact b of relay HS and back contacts b of relay MS and LS to the comparator.

Under medium speed selection, the circuit includes only front contact b of relay MS and the previously mentioned back contact b of relay L8. The circuit for applying a low speed request to the comparator includes back contact 0 of relay HS and front contact b of relay LS. When no signal is picked up from the signal rail by the train-carried apparatus, thus designating a zero speed requirement, a corresponding request is applied to the comparator over back contacts b, in series, i

plifier of any well known and satisfactory type which detects whether a propulsion or braking operation is required and controls the corresponding means, as indicated by the flow arrows. such control persists until the desired and actual speed signals are of equal degree ill or level. Thereafter the comparator and control amplifier arrangement acts to maintain the desired speed condition.

The door open relay DO on the train is controlled in a more direct fashion from the wayside and not through the signal rails as previously described in HQ 1. Relay D is controlled directly by a reed relay which responds to an external magnetic influence to close its single set of contacts to apply energy to the winding of relay DO through a time delay element DOT. Such reed delays are known in the art, are frequently used, and respond to an external magnet source to close their contacts. In this case, the permanent or electromagnet is mounted on the station platform in a position closely adjacent to that which the reed relay, mounted on the train occupies when a station stop has been completed. Thus the magnet influences the reed relay to complete the circuit for relay DO. The time delay unit DOT represents a slow release control for relay DO, as further designated by the downward pointing arrow drawn through the movable portion of contact a of this latter relay. Several types of delay operation are possible, depending upon the design of the system. For example, unit DOT may interrupt the energizing circuit for relay DO after a predetermined period of time and allow the relay to release. Alternatively, the time delay may be used to interrupt the energization of a wayside electromagnet so that the reed relay opens its contacts and allows relay D0 to release. A further arrangement provides that control of relay DO by the reed relay may be only momentary and unit DOT then holds relay DO energized for the predetermined period. In any event, once energized and picked up, relay DO must retain its front contacts closed for the preselected period during which the'car doors are to be held open. In whatever fashion the relay DO time delay is controlled, its timing I period of slow release and the slow pick up period for relay LS, that is, the time delay periods of units DOT and LST, must be correlated in order to assure that relay DO has released prior to the pick up of relay LS. The door control circuits act when relay D0 is picked up to apply a conventional open door signal to a door control unit over back contact a of relay LS and front contact a of relay DO. The door control unit, thus actuated, causes the car doors to open. At the close of the period, relay DO releases and closes its back contact a to apply a corresponding close door signal to the door controller which then operates to cause the car doors to close.

I shall now describe the operation of the arrangement of FIG. 2. Assuming that the train represented by the block V has entered section AT, the high voltage, positive polarity signal received on board the train properly energizes relay HS to pick up its contacts. It is obvious that relay MS is energized with opposite polarity energy in accordance with its winding symbol and thus remains released. At the same time, relay LS remains deenergized by the open back contact a of relay HS. A high speed request signal is applied to the comparator over front contact b of relay HS and back contacts b of relays MS and LS. The remainder of the apparatus functions to control the train movement to attain the desired, highest allowed speed. In other words, the propulsion means is controlled in accordance with the signal from the control amplifier to cause the train to proceed forward at this speed.

When the train enters section ET, the train apparatus receives a high voltage, but reverse polarity signal. Under these conditions, relay HS is reverse energized and releases while relay MS picks up. The open back contact a of relay MS under these conditions assures that relay LS remains deenergized. A medium speed signal is applied over the now closed front contact b of relay MS and back contact b of relay LS to the comparator and this unit in turn outputs a signal which causes the control amplifier to reduce the train speed and then maintain it at the medium speed level. Upon entry into section CT, the train receivers no signal from the wayside to which any of its train-carried relays is responsive. Thus all speed relays are released and the circuit over their back contacts b in series applies a zero speed signal to the comparator. This causes the signal applied to the control amplifier to actuate a train braking action to stop the train.

Since CT is a relatively short section, the train soon enters section ST where it receives a low voltage, positive polarity signal but pick up of relay LS is delayed by unit LST for a preselected time period following this occurrence. The train thus continues its braking action until it stops at the platform. The design of the system parameters is such that the reed relay is then opposite the platform magnet and responds by closing its contacts to energize relay DO. ln whatever specific method is used, the time delay unit DOT begins its timing period at this time. However, relay DO picks up, closing its front contact a to complete the circuit over back contact a of relay LS to apply the open door signal to the door controller. At the end of the timing period of unit DOT, relay DO releases, this action occurring prior to the termination of the time delay period of unit LST. The closing of back contact a of relay DO actuates the closing of the car doors. Shortly following, the timing period of unit LST expires and, since relays HS and MS are both released, relay LS can be energized over back contacts a of relays HS and MS by the received signal. When the relay LS picks up, the low speed request signal is applied to the comparator and, since the car doors are already closed, this unit acts to output a signal to the control amplifier to initiate forward movement of the train. Since a zero speed condition exists, the propulsion means are actuated to attain the low speed level. The train leaves the station at low speed but shortly thereafter enters section 2AT where once again it receives a high voltage, positive polarity signal which conditions the train apparatus to request and attain a high speed movement. The operating cycle then repeats as the train moves on towards the next sta tion.

The arrangement of my invention thus provides a relatively simple system for controlling the speed of a train moving along a nonconducting guideway. The signals are applied to a special transmission channel along this right-of-way and are received by the train apparatus which selectively responds to attain a desired speed for the train or to perform other designated functions. The apparatus is simple in nature and yet fail-safe in operation. The result is an efficient, economical, and fail-safe speed control arrangement particularly adaptable to and usable for PRT type transportation systems.

Although l have herein shown and described but two forms of apparatus embodying the principles of the speed control system of my invention, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention. I 7

Having now described the invention what -I claim as new and desire to secure by Letters Patent, is:

l. A train control system for trains traversing a fixed right-of-way, comprising in combination,

a. a signaling channel comprising a first and second conductor extending parallel to said right-of-way, 1. said first conductor being divided into a plurality of separate sections to form corresponding adjacent channel sections,

2. said second conductor being electrically continuous and connected to a system common bus,

b. a signal source connected to each first conductor section and to said common bus for transmitting through each channel section a signal having a predetermined distinctive characteristic,

c. control apparatus on each of said trains coupled across said first and second conductors for receiving the signal transmitted by said source through the section then occupied by that train,

d. said control apparatus on each of said trains also coupled for controlling selected train functions in response to the distinctive characteristic of the received signal. I

2. A train control system as defined in claim 1 in which,

a. each train-carried control apparatus comprises a plurality of relays, each responsive to a different one of the plurality of distinctive signal characteristics transmitted through said first conductor sections,

b. each relay is coupled for controlling a different controllable function on the corresponding train when a signal having the associated characteristic is received.

3. A train control system as defined in claim 2 in which,

a. each train-carried relay is of a direct current biased type having a preset required operating voltage level different from at least one other of said plurality of relays,

b. said signal source is a direct current energy source with end terminals of opposite polarity and a midpoint terminal connected to said common bus,

c. a preselected end terminal of said source is con nected to each first conductor section through a resistance of selected value to apply a predetermined voltage level signal, and

d. each relay being coupled to said first and second conductors for responding only to received signals of a predetermined polarity and having a voltage level providing at least the required operating voltage of that relay.

4. A train control system as defined in claim 3 which further includes,

a. a reed relay control means on each train coupled for controlling the train doors when actuated,

b. a magnet means at each station along said rightofwaypositioned for actuating the reed relay on each train when stopped at that station, and in which,

c. said biased relays on each train are coupled to train propulsion means for controlling train speed to a plurality of different levels determined by the dis tinctive signal received from said channel.

5. A train control system as defined in claim 4 in which,

said biased relays are further coupled to the train braking means for activating a brake application to 5 stop the train when no distinctive signal is received.

6. A train control system as defined in claim 2 in which, at least one of said plurality of relays is coupled for actuating train movement along said right-of-way at I a preselected speed only when the corresponding distinctive signal characteristic is received from said channel.

7. A train control system as defined in claim 6 which further includes,

a. a train detection means coupled between each first conductor section and said common bus,

b. each train detector means receiving the signal transmitted from said source to the associated section, when no train occupies the corresponding right-of-way section, and responsive to the received signal for registering the nonoccupied condition of that corresponding section,

0. said train detection means further coupled for inhibiting the transmission ofa distinctive movement control signal from said source to any first conductor section between adjacent stations until a train, once detected in any of the corresponding sections, has departed from that station-to-station stretch of said right-of-way.

8. A train control system as defined in claim 1 in which,

a. said signal source is a direct current energy source having end terminals of opposite polarity and a center tap connected to said common bus,

b. said control apparatus includes four biased direct current relays having at least two different predetermined operating voltage requirements,

(1) said relays so coupled to the channel conductors to establish a different operating characteristic, including voltage and polarity requirements, for each relay,

c. a preselected end terminal of said signal source is connected to each first conductor section through a resistance of selected value for supplying a signal of selected polarity and voltage level to that channel section,

d. each relay further coupled for controlling a different controllable function on the corresponding train when the received signal has the corresponding operating characteristic,

1. at least one relay controlling the speed of train movement, and

2. at least another relay controlling the train door operation at station platforms.

9. A train control system as defined in claim 8 which further includes,

a. a train detection means coupled between each first conductor section and said common bus,

b. each train detection means receiving the signal ratus for activating a brake application to stop the train when no signal is received and to hold the train halted when only a door control signal is received. 

1. A train control system for trains traversing a fixed rightof-way, comprising in combination, a. a signaling channel comprising a first and second conductor extending parallel to said right-of-way,
 1. said first conductor being divided into a plurality of separate sections to form corresponding adjacent channel sections,
 2. said second conductor being electrically continuous and connected to a system common bus, b. a signal source connected to each first conductor section and to said common bus for transmitting through each channel section a signal having a predetermined distinctive characteristic, c. control apparatus on each of said trains coupled across said first and second conductors for receiving the signal transmitted by said source through the section then occupied by that train, d. said control apparatus on each of said trains also coupled for controlling selected train functions in response to the distinctive characteristic of the received signal.
 2. A train control system as defined in claim 1 in which, a. each train-carried control apparatus comprises a plurality of relays, each responsive to a different one of the plurality of distinctive signal characteristics transmitted through said first conductor sections, b. each relay is coupled for controlling a different controllable function on the corresponding train when a signal having the associated characteristic is received.
 2. said second conductor being electrically continuous and connected to a system common bus, b. a signal source connected to each first conductor section and to said common bus for transmitting through each channel section a signal having a predetermined distinctive characteristic, c. control apparatus on each of said trains coupled across said first and second conductors for receiving the signal transmitted by said source through the section then occupied by that train, d. said control apparatus on each of said trains also coupled for controlling selected train functions in response to the distinctive characteristic of the received signal.
 2. at least another relay controlling the train door operation at station platforms.
 3. A train control system as defined in claim 2 in which, a. each train-carried relay is of a direct current biased type having a preset required operating voltage level different from at least one other of said plurality of relays, b. said signal source is a direct current energy source with end terminals of opposite polarity and a midpoint terminal connected to said common bus, c. a preselected end terminal of said source is connected to each first conductor section through a resistance of selected value to apply a predetermined voltage level signal, and d. each relay being coupled to said first and second conductors fOr responding only to received signals of a predetermined polarity and having a voltage level providing at least the required operating voltage of that relay.
 4. A train control system as defined in claim 3 which further includes, a. a reed relay control means on each train coupled for controlling the train doors when actuated, b. a magnet means at each station along said right-of-way positioned for actuating the reed relay on each train when stopped at that station, and in which, c. said biased relays on each train are coupled to train propulsion means for controlling train speed to a plurality of different levels determined by the distinctive signal received from said channel.
 5. A train control system as defined in claim 4 in which, said biased relays are further coupled to the train braking means for activating a brake application to stop the train when no distinctive signal is received.
 6. A train control system as defined in claim 2 in which, at least one of said plurality of relays is coupled for actuating train movement along said right-of-way at a preselected speed only when the corresponding distinctive signal characteristic is received from said channel.
 7. A train control system as defined in claim 6 which further includes, a. a train detection means coupled between each first conductor section and said common bus, b. each train detector means receiving the signal transmitted from said source to the associated section, when no train occupies the corresponding right-of-way section, and responsive to the received signal for registering the nonoccupied condition of that corresponding section, c. said train detection means further coupled for inhibiting the transmission of a distinctive movement control signal from said source to any first conductor section between adjacent stations until a train, once detected in any of the corresponding sections, has departed from that station-to-station stretch of said right-of-way.
 8. A train control system as defined in claim 1 in which, a. said signal source is a direct current energy source having end terminals of opposite polarity and a center tap connected to said common bus, b. said control apparatus includes four biased direct current relays having at least two different predetermined operating voltage requirements, (1) said relays so coupled to the channel conductors to establish a different operating characteristic, including voltage and polarity requirements, for each relay, c. a preselected end terminal of said signal source is connected to each first conductor section through a resistance of selected value for supplying a signal of selected polarity and voltage level to that channel section, d. each relay further coupled for controlling a different controllable function on the corresponding train when the received signal has the corresponding operating characteristic,
 9. A train control system as defined in claim 8 which further includes, a. a train detection means coupled between each first conductor section and said common bus, b. each train detection means receiving the signal transmitted from said source to the associated section, when no train occupies the corresponding right-of-way section, and responsive to the received signal for registering the nonoccupied condition of that corresponding section. c. said train detection means further coupled for inhibiting the transmission of a distinctive movement control signal from said source to any first conductor section between adjacent stations until a train, once detected in any of the corresponding sections, has departed from that station-to-station stretch of said right-of-way.
 10. A train control system as defined in claim 9 in which, said relays are also coupled to the train brAking apparatus for activating a brake application to stop the train when no signal is received and to hold the train halted when only a door control signal is received. 